This invention relates to the field of drive means for oscillating spouts. More particularly, this invention relates to a new and improved apparatus for driving an oscillating spout for a shaft furnace, the spout being capable of pivoting about two orthogonal axes under the action of a pivoting control arm.
Apparatus of this general type has been described in French Patent Application A-80 13890 corresponding to U.S. Pat. No. 4,306,827, which relates to an apparatus for distribution of charge material in a blast furnace. This French patent application includes an intermediate lever which, together with a control arm, form a rotating hinge having a variable angle of opening (i.e., the included angle). It is this angle of opening which determines the angle of inclination of the control arm and that of the spout in relation to the vertical axis of the furnace. The French patent application also includes a control mechanism which consists essentially of a driving rod capable of pivoting about its longitudinal axis and undergoing axial displacement in order to increase or reduce the "included" angle of the hinge. In order to achieve this action, the driving rod is provided with channel sections for sliding longitudinally therein, under the action of a first motor, inside a rotary socket which is capable of rotating under the action of a second motor.
Unfortunately, the control mechanism of the French patent application is deficient in that relatively high mechanical stresses are concentrated in the position corresponding to the channeled sections. These high stresses have a tendency to render the driving rod immobile in rotation with the outer driving socket. In other words, the stresses will often impede the sliding movement of the rod inside the socket and thereby cause premature wear. Moreover, in order to resist these mechanical stresses, the driving rod of the French patent application must be supported and guided at a plurality of levels; which provides the additional disadvantage of increasing the height of the driving device and of increasing the overall space occupied by the control mechanism.